Summary of Transactions in the ALLL by Portfolio segment (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended			6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012	Jun. 30, 2013		Jun. 30, 2012
Beginning Balance	$ 1,783		$ 2,126	$ 1,854	[1]	$ 2,255
Losses charged off	(145)		(219)	(313)		(472)
Recoveries of losses previously charged off	33		38	68		71
Provision for loan and lease losses	64		71	126		162
Ending Balance	1,735	[1]	2,016	1,735	[1]	2,016
Commercial Portfolio Segment
Beginning Balance	1,191		1,424	1,236	[2]	1,527
Losses charged off	(59)		(95)	(128)		(211)
Recoveries of losses previously charged off	14		17	29		33
Provision for loan and lease losses	37		1	46		(2)
Ending Balance	1,183	[3]	1,347	1,183	[3]	1,347
Residential Mortgage Loans
Beginning Balance	212		233	229	[2]	227
Losses charged off	(18)		(38)	(40)		(76)
Recoveries of losses previously charged off	3		2	5		3
Provision for loan and lease losses	4		35	7		78
Ending Balance	201	[3]	232	201	[3]	232
Consumer Portfolio Segment
Beginning Balance	272		341	278	[2]	365
Losses charged off	(68)		(86)	(145)		(185)
Recoveries of losses previously charged off	16		19	34		35
Provision for loan and lease losses	27		42	80		101
Ending Balance	247	[3]	316	247	[3]	316
Unallocated
Beginning Balance	108		128	111	[2]	136
Provision for loan and lease losses	(4)		(7)	(7)		(15)
Ending Balance	$ 104	[3]	$ 121	$ 104	[3]	$ 121

[1] Includes $50 and $50 of commercial mortgage loans, $(13) and $(5) of ALLL, and $1 and $3 of other assets from consolidated VIEs that are included in their respective captions above at June 30, 2013 and December 31, 2012, respectively. See Note 8.

[2] Includes $11 related to leveraged leases.

[3] Includes $10 related to leveraged leases.